Stihl 064 carb tuning trouble

[t_andersen]

Hi Guys,

My Stihl 064 was hard to start, and I believe that it was due to the carb. It had a Bing carb and since a carb kit for the Bing is rather expensive, I bought a brand new complete Walbro carb and installed it on my saw. Initially I put the H and L screws one turn counterclockwise and fired the saw up. It idled well right from the start, so I went to tuning the H screw using a tachometer. While fiddling with the screw, something happened and suddenly it wouldn’t idle anymore. I could start it ok but it kept stopping when idling no matter how I set the L screw and the idle screw. I waited for some hours and tried again but then it wouldn’t even start.

Will someone be kind enough to suggest a procedure for diagnosing what is wrong? I really don't know how to go ahead. I am somewhat desperate, having installed a brand new carb and now I can’t even get the d’d thing to run! And I have three oak logs waiting to be slabbed!

Thanks

Tom

 

[Lakeside53]

Reset your carb to 1 turn out.

If you didn't change the filter and blow out the fuel hose, you may have sucked crud into the carb filter (inside under the pump diaphragm).

Additionally, you may have a tank vent problem (open gas tankcap a little and see if the problem goes away) or, your impulse line is faulty, or your fuel hose/filter are faulty...

First question to resolve is whether its getting too much or too little gas to start/run.

 

[Simonizer]

Hi Guys,

My Stihl 064 was hard to start, and I believe that it was due to the carb. It had a Bing carb and since a carb kit for the Bing is rather expensive, I bought a brand new complete Walbro carb and installed it on my saw. Initially I put the H and L screws one turn counterclockwise and fired the saw up. It idled well right from the start, so I went to tuning the H screw using a tachometer. While fiddling with the screw, something happened and suddenly it wouldn’t idle anymore. I could start it ok but it kept stopping when idling no matter how I set the L screw and the idle screw. I waited for some hours and tried again but then it wouldn’t even start.

Will someone be kind enough to suggest a procedure for diagnosing what is wrong? I really don't know how to go ahead. I am somewhat desperate, having installed a brand new carb and now I can’t even get the d’d thing to run! And I have three oak logs waiting to be slabbed!

Thanks

Tom

Whoa, back up the train buddy. A Bing carb kit was more expensive than a Walbro carb? I will endeavor to assist you. 1. Muffler off, inspect piston/cylinder. 2. Pressure/vacuum test on crankcase. If this is all good, put a kit in your Bing and take the Walbro back and pay the re-stocking fee. We will go from there. Cheers.

 

[t_andersen]

Thanks for your answers so far!

Reply to Lakeside53:

When I got the trouble, I reset H and L to 1 turn out and it still won't start.

Reply to Simonizer:
I have checked the cylinder, no scoring, and I have measured the compression to 125, a little on the low side I guess. I got the new Walbro carb on e-bay, cost was 34.99 $ from "stihlstuff". I have been told that the Bing carb kit is around 20 $.

I'll check the other things on the saw tomorrow morning.

 

[Simonizer]

Thanks for your answers so far!

Reply to Lakeside53:

When I got the trouble, I reset H and L to 1 turn out and it still won't start.

Reply to Simonizer:
I have checked the cylinder, no scoring, and I have measured the compression to 125, a little on the low side I guess. I got the new Walbro carb on e-bay, cost was 34.99 $ from "stihlstuff". I have been told that the Bing carb kit is around 20 $.

I'll check the other things on the saw tomorrow morning.

The pressure/vacuum leakage test on the crankcase is the most important test you can perform.

 

[PWB]

Sorry to cut in on the thread, but I have a similar problem with an 064. Saw runs great once I get it started the first time. Trouble is, it won't draw gas up the first time. Pull it as many times as you like, it's a lost cause. give a little shot of gas in the carb, starts and runs like a champ. Starts and stops fine all day. I'm a weekend cutter usually, maybe a little after work during the week once in a while. If the saw sits all week, I've got the same problem next weekend. One little shot of gas in the carb, away we go. Where do I look? Diaphram? impulse? Saw has loads of compression, outcuts an 066 dual port we have at work.

 

[stihltech]

leaks

Get those saws pressure and vacuum tested. The statement that they run really well, but don't idle, scares me. Usually the logger says that and then brings it in lean seized in about a week.

 

[t_andersen]

Thanks for the comments. I don't have the official Stihl vacuum/pressure test equipment. Is there any clever way to make measurements without the official gear? How about a bicycle pump (with the piston turned for vacuum?

By the way, I inspected the filter inside the carb and it's clean, so that's not the cause...

 

[PWB]

I know why you want the tests, but I don't have an idle problem with mine. Once started, it will idle all day if so desired. runs exactly like it's supposed to other than doesn't draw gas at the first start.

 

[KASH]

I had the same problem with my 038 mag and a few other saws over the years. I find if you open the slow speed needle a bit it usually cures the starting problem, Hope this helps.

 

[Lakeside53]

I had the same problem with my 038 mag and a few other saws over the years. I find if you open the slow speed needle a bit it usually cures the starting problem, Hope this helps.

I think you mean the Low needle...

 

[KASH]

Lakeside53
Your correct I was thinking in outboard motor lingo. Sorry about the confusion.